/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

package org.apache.druid.segment.join;

import org.apache.druid.query.DataSource;
import org.apache.druid.query.Query;
import org.apache.druid.query.planning.DataSourceAnalysis;
import org.apache.druid.segment.SegmentReference;

import java.util.Collections;
import java.util.List;
import java.util.Set;
import java.util.concurrent.atomic.AtomicLong;
import java.util.function.Function;

/**
 * A datasource that returns nothing. Only used to test un-registered datasources.
 */
public class NoopDataSource implements DataSource
{
  @Override
  public Set<String> getTableNames()
  {
    return null;
  }

  @Override
  public List<DataSource> getChildren()
  {
    return null;
  }

  @Override
  public DataSource withChildren(List<DataSource> children)
  {
    return null;
  }

  @Override
  public boolean isCacheable(boolean isBroker)
  {
    return false;
  }

  @Override
  public boolean isGlobal()
  {
    return false;
  }

  @Override
  public boolean isConcrete()
  {
    return false;
  }

  @Override
  public Function<SegmentReference, SegmentReference> createSegmentMapFunction(
      Query query,
      AtomicLong cpuTime
  )
  {
    return Function.identity();
  }

  @Override
  public DataSource withUpdatedDataSource(DataSource newSource)
  {
    return newSource;
  }

  @Override
  public byte[] getCacheKey()
  {
    return new byte[]{};
  }

  @Override
  public DataSourceAnalysis getAnalysis()
  {
    return new DataSourceAnalysis(this, null, null, Collections.emptyList());
  }
}
